The present invention relates to a composite pellicle for producing thermographic representations. Such a composite pellicle serves to indicate the temperature at each point of a surface, that is to say the thermal state of this surface. The invention is concerned more particularly, but not exclusively, with the study of the distribution of the temperature at the cutaneous surface of an individual.
The representation of the distribution of the cutaneous temperatures can expose anomalies of temperature and make it possible to observe thermopathic-physiological phenomena, such as superficial veinous phenomena, and thus allows a physician to establish his diagnosis with greater certainty and rapidity. The precision and quality of such representation therefore assumes a great importance, in the degree to which an improvement in this precision makes it possible to reveal cutaneous temperature anomalies which would otherwise not be discernible. In particular, such a composite pellicle is applicable to the detection of mammary anomalies (cancer of the breast).
Thermographic representations have already been made with the use of infrared cameras, without contact between the surface being examined and the camera. Likewise thermographic representations have been made with the use of temperatureresponsive substances, mainly liquid crystals, nearly always necessitating a contact between the surface to be thermally examined and the sensor (the liquid crystals). These crystals may be deposited upon the said surface, for example like a paint, or applied through the intermediary of a flexible support disposed against the surface to be examined and conforming to this surface. There have also been utilised supports called "thermosensitive pellicles with liquid crystals".
Such pellicles are currently in use. It is known that the different parts of the pellicle take on colours which are dependent upon the temperature. Upon being applied to a surface such a pellicle assumes at each point a temperature close to that of the surface in contact, and a corresponding colouration. The representation furnished by the pellicle, which can be photographed, is a thermal image which theoretically makes it possible to know the temperature at each point. However these devices do not give complete satisfaction and are sometimes very unsatisfactory. These pellicles are fragile and easily tear or become damaged. Liquid crystals change colour only for certain respective temperatures, and it is well known that outside of a respective range of temperatures the crystals do not change colour, they are saturated and their colour gives no precise indication. Finally the diffusion of the temperature within the plane of the pellicle shows inequalities, sometimes sufficient to obscure the localised anomalies.
One object of the present invention is to provide a composite pellicle for making thermographic representations by means of thermosensitive layers of liquid crystals avoiding or mitigating the disadvantages indicated above.